The present invention relates to a numerical control apparatus and, more particularly, to a numerical control apparatus which can easily control a mirror image function from a program.
A conventional numerical control apparatus is known which has a mirror image function for inverting a shift amount instruction code of a machining program using switches on an operation panel of the numerical control apparatus, or using the program itself. In a conventional numerical control apparatus of this type, as shown in FIG. 1, a workpiece is machined to a shape AX derived from a shape A defined by points P1, P2 and P3 when a mirror is placed at a position XM along the X axis, a shape AY derived from the shape A when the mirror is placed at a position YM along the Y axis, or a shape AXY when mirrors are placed at the positions XM and XY along the X- and Y-axes. Such machining can be performed using a mirror image function without entering a shape AX, AY, or AXY instruction.
The conventional mirror image function, however, can only be turned on or off by a switch or a program; mirror position cannot be designated. For this reason, a shape to be subjected to mirror image processing must be shifted to a position where a mirror has been placed.